[nickcarraway]

Presumably, because he had a twin. Some people believe Matthew is his twin, but there doesn't seem to be much evidence of this, so most likely his twin is unknown. The Acts of Thomas says he was called the twin because he looks so much like Jesus, and some groups claimed he actually was a twin of Jesus.

[FamiliarFace]

I always have wondered if Thimas looked like Jesus. One of the reasons that Judas Iscariot had to kiss Jesus was to show that He was the right one to arrest. So, in my mind, there’s something to Thomas looking like Jesus, and vice versa.